This application claims the priority of German Application No. 102 37 040.0 filed Aug. 7, 2002, the disclosure of which is expressly incorporated by reference herein.
The present invention relates to an arrangement for sealing an opening of a rotor housing in which a vacuum prevails, through which opening a shaft, supported outside of the rotor housing, projects, said arrangement comprising at least two sealing gaps, of which a first sealing gap is formed between the shaft and a sealing element free floating in relation to the opening, while a second sealing gap is formed with a collar of the spinning rotor bordering on the shaft.
An arrangement of this type is prior art in German published patent application DE 197 32 096 (corresponding U.S. Pat. No. 6,095,529). The sealing element is in this case a free floating sealing disc, which seals the shaft from a ring-shaped component which is clipped onto the rotor housing. The second sealing gap is independent of the free floating sealing disc and is located between the collar of the spinning rotor and a plastic tube affixed in the rotor housing. Because of the combination of the two sealing gaps, a kind of labyrinth sealing occurs, which makes it difficult for unwanted air to enter into the rotor housing. Overall, a non-contact seal occurs, which permits, for example, the spinning rotor to be pulled out of its bearing towards the operator's side out of the open-end spinning aggregate. In order not to permit the two sealing gaps to become too large, despite this dismounting possibility of the spinning rotor, the through entry bore hole of the free floating sealing disc has a narrow tolerance in relation to the shaft, which in turn permits the sealing disc, as a result of its free floating arrangement, to center itself when the machine is set in operation.
Spinning rotors can operate today at speeds of approximately 150,000 rpm. Such high speeds are only possible when the distances between the shaft bearings are relatively short and in addition, when the part of the spinning rotor located in the rotor housing has only a relatively small overhang in relation to the next bearing. This has the result that in the known arrangement, the first sealing gap between the free floating sealing disc and the shaft is very short, so that the first bearing located outside of the rotor housing can be moved very close to the rotor housing.
It is an object of the present invention to make the sealing gap as long as possible in order to achieve as effective gap sealing as possible in an area where the sealing gap can be narrowly tolerated.
This object has been achieved in accordance with the present invention in that the second sealing gap is also formed with the same free floating arranged sealing element.
With preferred embodiments of the invention, the first sealing gap is extended by means of the second sealing gap, whereby in both cases one and the same sealing element acts together with the spinning rotor, that is once with the shaft and once with the collar. Thus both sealing gaps can be very narrowly tolerated. The sealing gap hereby becomes significantly more effective in preventing the entry of false air. With certain preferred relevant embodiments, an additional, radially extending sealing gap forms automatically at the end of the collar where it graduates over to the shaft.
The sealing element preferably comprises a radial flange which is disposed free floating with respect to a likewise radially formed supporting surface of the rotor housing, and also comprises a tube-like area arranged to the collar. The result is a preferably one-piece combined component for the free floating sealing element, which component can simultaneously run in at both sealing gaps when the machine starts up. It is hereby advantageous according to preferred embodiments when the radial flange is pressed against the support surface by at least one spring element. Although this is not strictly necessary due to the low pressure in the rotor housing, the spring element provides additional security, in particular when the spinning aggregate has to be opened for maintenance purposes and the low pressure collapses as a result.
In certain preferred embodiments of the present invention it is provided that the sealing element in addition comprises a sealing surface extending essentially radially and forming a third sealing gap with the rear wall of the spinning rotor. This sealing surface need not be absolutely radially arranged, but rather can be more or less conically formed. The free floating sealing element is in this way placed sufficiently close to the rotating spinning rotor, whereby the drawing in of air is rendered more difficult. A type of envelopment of the spinning rotor occurs, at least in part, at its rear wall, whereby, above all at high surface speeds, a reduction in energy consumption can be achieved. Because the sealing surface, being applied to the free floating sealing element, is also aligned according to the shaft, it can be placed accordingly close to the surface of the rear wall of the spinning rotor.
The said envelopment of the rear wall of the spinning rotor can be further improved when the sealing surface is provided with a hollow cylindrical extension which envelopes a cylindrical area of the rear wall. In combination with said gap sealing, a further, fourth sealing gap occurs due to this improved enveloping of the spinning rotor, namely between the hollow cylindrical extension of the free floating sealing element and the cylindrical area of the rear wall of the spinning rotor.
A particular advantage arises when the sealing surface can be arranged at an exchangeable part which is connectable to the sealing element. This exchangeable part, which can be connected in one piece with, but releaseable from, the free floating sealing element, can be adapted to various diameter areas of the spinning rotor. It is purposeful when the exchangeable part is pressed onto the tube-like area.
These and further objects, features and advantages of the present invention will become more readily apparent from the following description of a greatly enlarged embodiment of the present invention when taken in conjunction with the accompanying drawing.